Glue mix



United States PatetltOf GLUE MIX Carl E. Drugge, Long Beach, Calif., and JohnM. Hinc, Seattle, Wash., assignors to The Borden Company, New York, N.Y., a corporation of New Jersey No Drawing. Filed Apr. 11, 1957, Ser. No. 652,114

7 Claims. (Cl. 260--8) This invention relates to a glue mix and, more particularly, to a glue mix comprising a proteinaceous material and polyvinyl acetate and which glue mix is'especially useful ,inthe manufacture of laminates typical of which are paper-wood-paper laminates. t i

This glue mix is especially desirable in the manufacture of paper-box shook which is a material of construction comprising a wood veneer core covered on-each face by paper. In the manufacture of shook, wood veneer having a moisturecontent in the range of seven to fifteen percent by weight is surfaced on each face with a heavy construction paper such as kraft paper. The paper may be moistened on one side with water, or preferably, with a wax-water emulsion. However, the moistening of the paper is not an essential step tot h e manufacturing operation. The other face of the paper is coated with a gluemix and that side which is coated with the glue-mix is pressed against the wood veneer so as to contact the wood and the paper. With each face of the wood veneer covered by a paper, the resulting shook is squeezed between pressure rolls so as to more evenly distribute the moisture in the veneer and paper with the result that the glue partially sets due to the squeezing of the moisture out of the glue and into both the paper-and the wood; Also, there may be' concurrently with this squeezing operation a heating step to set the glue while under pressure. Or, the heating step may follow the squeezing operation so as to set the 'glueindependent of the pressure step. One of the characteristics making it possible to overlay the paper on the wood veneer without distortion of either providea glue-mix possessing the ability to quick-set or cure rapidly at, a relatively low temperature. 7 Another object of this invention is the provision of a glue-mix which is water resistant or resists the action of water when in the cured state between the paper andl the veneer. a

A further object of this invention is to provide a" gluemix which is spread'easily' onto a material such as paper or wood veneer. I f j A still further and important object is the provision of a glue-mix which possesses sufficient tack to be of value in the formation of veneer products such as plywood and paper-wood veneer-. v p 1 An additional Object'of this invention is the provision of a glue-mix which is relatively low incost for its bonding properties and specific "uses;

2,963,454 Patented Dec. 6, 1960 2 Various other ancillary objects and advantages of the present invention will become apparent in the following description and explanation of the same.

Turning now to the invention it is seen that the same comprises a glue-mix having as a base a proteinaceous material and polyvinyl acetate. In addition to these components there are other auxiliary components. The combination of the components functions to bring out and enhance the desirable properties. of the individual components so that the resulting glue-mix displays an ability to set quickly or cure quickly at a relatively low temperature; in the cured state to resist the action of water, and also to be easily spread in the liquid state.

In particular, with regard to the-proteinaceous material, there may be used soya bean flour, free of oil, and of a size approximately one hundred mesh or smaller. Also, there may be employed cotton seed flour and linseed flour, both free of oil, and of a size one hundred mesh or smaller. In addition, other suitable proteinaceous materials are casein, soluble dried blood, and isolated soya protein. With particular reference to dried blood, the same is obtained from slaughter houses. Normally, because of the diiferent animals being butchered, this dry soluble blood is a mixture of blood from beef, sheep, and hogs. Although the blood of beef andsheep may be used alone without admixture fromother blood, it is recommended that hog blood be used not by itself but as a modifier for the blood of either the beef or the sheep or a mixture of these two. The blood is collected and dried in a convenient manner such as by spraying. In the drying of the blood care is taken so as not to heat the blood to its coagulating temperature of approximately F. or above. In the dry form, the blood keeps substantially unchanged for an indefinite period of time.

I The polyvinyl acetate maybe in a number of different forms. However, the form we have satisfactorily used is an aqueous emulsion containing approximately 55% solids and having a viscosity in the range of 1150-1400 cps. at 25 C. A commercial source for this polyvinyl acetate is Polyco 11785.

In addition to the proteinaceous material and the polyvinyl acetate there are a number of other constituents. For example, the glue-mix is usually of an alkaline pH and has incorporated therein inorganic materials such as lime and/or sodium hydroxide. In regard to the lime, this component functions to increase the water resistance of the cured glue so that when the same is between veneers there is less possibility of water decreasing the bonding power of the glue with subsequent delamination of the veneers. Also, the lime serves another purpose in that with the lime present the glue-mix appears to set or cure more rapidly than when the lime is not present. The reason for this increase in setting speed may be due to an interaction between calcium ions and polyvinyl acetate. The sodium hydroxide actsas a solubilizing agent for the various components'in the glue-mix thereby making it possible to prepare a smoother glue-mix and one which spreads more easily. Another inorganic alkaline component which is incorporated into the glue-mix is sodium silicate. This material functions in a number of different ways, one of which is as a solubilizing agent for the components of the glue-mix so as to make a more smoothmix. Also, sodium silicate increases the adhe-w sion of the glue-mix to both the wood veneer and the paper overlay in paperbox shook, and functions to increase the water resistance of the cured glue thereby making a paper-wood-paper laminate which is not likely to delaminate upon exposure to the elements.

In this glue-mix there are incorporated fillers. From experience it is realized that it is possible to use fillers without unduly restricting the bonding power of the active ingredients. Numerous materials are suitable for this purpose, such as ground glass, diatomaceous earth, powdered clay, and organic materials of vegetable origin. More specifically, the organic materials may be Glufil, Furafil, or Silvacon-490. Glufil is comminuted walnut shells which have been cleaned prior to contrituration, and is a product of the Agrashell Corporation of Los Angeles, California. Furafil, either Furafil 100 or Furafil lO-S,-is a product obtained during the processing of corncobs to make furfural, an important industrial chemical. In this process the cobs are pressure cooked with steam and dilute acid, and, after the furfural has been distilled, the remaining residue, which looks somewhat like ground coffee, is milled to fiour fineness. This product Furafil 100, consists largely of modified cellulose, lignin and resinous materials. In the cooking of the corncobs there may be used a mineral acid, such as sulfuric or hydrochloric acid. Silvacon-490 is a finely powdered, brown colored amorphous material, thermoplastic by nature, obtainable from bark.

Other components of the glue-mix may be carbon disulfide, carbon tetrachloride, and pine oil. The carbon disulfide is beneficial as it increases the water resistance of the cured glue so as to decrease the possibility of delamination of the veneer in a laminate. In regard to the carbon tetrachloride, this component decreases the flammability of the carbon disulfide and thereby acts as a safety factor. And, the pine oil functions as a defoamer to decrease the foaming properties of the glue-mix and thereby make the same easier with which to work.

There are numerous desirable processes for the making of the glue-mix. Generally speaking, the components are mixed together in an aqueous medium for a sufiicient period of time to insure a careful blending of the same. Also, the components are usually added one at a time successively or else two at a time. A specific example of the making of the glue-mix is presented as follows. As is seen from this example upon the addition of the various components the mixture is agitated or mixed for asufiicient period of time to blend-in the component or components.

The following example specifically illustrates a mixing procedure used in the making of these glue-mixes.

Mix five minutes, hold to adjust viscc sity.

In another process dried blood is mixed with water until substantially dissolved therein and then various components are added to this mixture. For example, these components are defoamers, caustic dissolved in water, a lime slurry, sodium silicate, and polyvinyl acetate in "a 55% solids aqueous emulsion. Again, after the addition of each-component it is desirable to mix the resulting mixture for a sufficient period of time to insure the careful blending of the mixture. In another example a glue-mix is prepared from a base comprising casein powder and soya bean flour. The casein powder, soya bean flour, and water are mixed together'to form a smooth mixture. Then, to this mixture there is added/an waque'ousslurry of sodium hydroxide and the resulting mixture is mixed for a few minutes. A clay filler is then mixed in. Then water is added to the mixture to dilute the same, and finally polyvinyl acetate in a 55% aqueous emulsion is mixed into the mixture to make the glue-mix.

As an example of a specific use for these glue-mixes the same are employed in the manufacture of box-shook. This shook is prepared from dry wood veneer and a heavy industrial paper. More particularly, the veneer possesses a moisture content in the range of seven to fifteen percent (7l5%) and the paper may be forty-two pound kraft liner board. In the manufacture of the box-shook the paper is coated on one surface with the glue-mix and may be wetted on the other surface with water or waxwater emulsion. Then, the paper is applied to each face of the wood veneer with that side having the glue-mix thereon pressed against the veneer to form a paper-woodpapercomposite structure. This structure is pressed for a suitable period of time and at a desirable pressure and temperature. For example, the time may be eight seconds, the pressure may be twenty pounds per square inch, and the temperature approximately 200 F. Upon the completion of this cycle'the composite structure is a paperwood-paper laminate.

Specimens of the paper-wood-paper laminate are then tested for wood and paper failure. This test is known as PPP-V-00205b (USAF), USAF standing for United States Air Force. Briefly, this test comprises taking ten (10) test panels at random from any shipment. The test panels are selected to represent as many variations in grades and thicknesses as possible. From each panel selected a 6" x 6" test piece is cut from each end approximately at mid-width of the panel, and from each edge approximately at mid-length of the panel, while a fifth piece is cut from somewhere near the middle or center of the panel. The test pieces, 6" x 6", are submerged in Water at room temperature for a period of four (4) hours, and then dried at a temperature not to exceed 100 F. for a period of twenty (20) hours and sixty-five percent (65%) relative humidity. For three cycles of this soak and dry test there should be no delamination greater than two (2) inches in length between the paper and wood in order for the laminate to meet requirements for Type I of this specification. Furthermore, for a ten cycle soak and dry test there should be no visible delamination or separation at the glue line or Within the paper, in order for the laminate to satisfictorily pass the test for Type II.

Having presented in a general manner the components of the glue-mix and the method of making the glue-mix from these components, there are now presented specific examples of these glue mixes. However, it is to be realized that these examples are meant to be by way of illustration and are not meant as limitations upon the invention.

Alkaline Che'nlcals Buckeye Soya Fl ur, 77% Protein Polyvinyl Acetate Emulsion, 55% Polyvinyl 80 (36 fate. ga'iklay (clay, water washed) 25 50 50 ne Sodium hydroxide, 50% aqueous..." 3 10 10 Sodium silicate 5 Pine Oil 2 2 2 Water 277 525 500 Three glue-mixes were prepared from the above constituents. As is seen, A differed from B and C in that the proteinaceous material in A was soya bean flour whilein B and C the material was high protein soya flour. Also,

h forming no part of this invention differed from A and C in that A and C comprised polyvinyl acetate while B did not contain polyvinyl acetate. These glue-mixes were made into paper-wood-paper laminates having a Douglas fir core and a 42 pound kraft liner board as a facing. The laminates were prepared with a glue spread of 40-50 pounds per thousand square feet double glue line, a pressure of 20 p.s.i., a temperature of 200 F., and press times of 1, 2, 4, and 8 seconds. These laminates were tested by stripping the paper from the -wood im mediately after pressing. The results of these tests in terms of Percent paper fiber retained on wood are as follows: 1

Percent Paper Fiber Retained V p on Wood Press Times, (Seconds) Glue Mix A B I o These results show that the two glue-mixes, A and C, comprising polyvinyl acetate, possess a faster setting time and result in a more water-resistant bond than the gluemix not having polyvinyl acetate.

Example No. II This example comprised the following:

Preparation B, containing no polyvinyl acetate, is not a part ofthe invention but is included for contrast with the results of the invention.

As is seen from the above data there were prepared two glue-mixes which differed in that one contained polyvinyl acetate and the other did not contain polyvinyl acetate. With these two glue-mixes there were prepared a number of paper-w0od-paper laminates. These laminates comprised a Douglas fir veneer and 42 pound kraft liner board facing and were prepared with glue spreads in the range of 30 pounds per thousand square feet of double glue line, at a pressure of about 20 p.s.i., and a temperature of approximately 200 F. These laminates were pressed for different time periods of 1, 2, 4, and 8 seconds. Panels were cut from these laminates and tested according to'test PPP-V-OOZOS b (USAF). In the terms of this test the glue-mix containing polyvinyl acetate emulsion possessed the property of setting in a shorter period of time than the glue-mix not having polyvinyl acetate emulsion incorporated therein. Also, the glue-mix having polyvinyl acetate resulted in a stronger glue-line than the glue-mix not having polyvinyl acetate as the glue-mix mor resistant to action of Water than the glue-mix n ha n Polyvinyl a ta e 6 Example No. Ill This example comprised the following:

commercial soya bean glue, water, polyvinyl acetate emulsion, and a lime-water slurry. The glue-mixes were tested by making paper-wood-paper laminates having a 1 Douglas fir veneer core and a 42 pound kraft liner board paper with a glue spread of pounds per thousand square feet of double glue-line. These laminates were pressed at a temperature of about 200 F. and at a pressure of approximately 20 p.s.i. The press times for the laminates varied as indicated by the data in the following table. The effect of the various press times was evaluated by testing samples of the laminates for the percent fiber retained on the wood upon stripping the paper from the wood. The results are:

These laminates were also tested by water soaking. Actually, there were three difierent water soaking tests: a ten-cycle test according to PPP-V-OO205b (USAF); a ten day tap water soak in the temperature range of 15- 17 C.; and, a ten day ice water soak at a temperature blow 3 C. Upon the completion of the soaking periods the panels were evaluated by checking each panel for paper delamination and by removing the paper from both sides of the wood veneer and estimating the paper fiber retained on the wood as a percent of the total area. As a control check a dry panel was tested for delamination and the paper fiber retained on the wood veneer. The results of these tests are presented in the following table.

Percent Paper Fiber Retained on Wood Laminate D 10 d d Y ay 10 ay Control IO-cycle Tap Wa- Ice Water Soak ter Soak In all of these panels there was no paper delamination for any of the panels and all panels completely passed the water resistance test.

The 400 parts of the polyvinyl acetate emulsion was dispersed in 300 parts of water to make a dispersion or 7 the same and to this there was added and mixed 200 parts of soya bean flour (100 mesh or finer). Then there was added a lime slurry having 50 parts of lime and 100 parts of water to make a glue-mix. With this glue-mix there was bonded to each side of a green Douglas fir veneer, A a kraft liner board, 42 pound weight. The bonding operation comprised 12 seconds of press time, a pressure of 20 p.s.i., and a temperature of 200 F. There resulted an excellent bond between the paper and the veneer and the paper-wood-paper laminate exhibited excellent water resistance as measured by test PPP-V-00205b (USAF).

Example N0. V This example comprised the following:

in preparing this glue 150 parts of a commercial blood glue containing approximately 80% of dried soluble blood was mixed with 178 parts of water. To this aqueous mixture there was added and mixed in about 628 parts of water to form an aqueous blood glue. To this aqueous blood glue there was added and mixed in approximately 4 parts of pine oil; 12 parts of caustic soda dissolved in 12 parts of water; 10 parts of lime slurried in 20 parts of water; 50 parts of sodium silicate; and 100 parts of a polyvinyl acetate emulsion having approximately 55 solids content to make a desirable glue-mix for bonding together wood and a felted fibrous sheet.

Example N0. VI

This example comprises the following:

Components: Parts by weight Casein powder (30 mesh or finer) 60 Soya bean flour (200 mesh or finer) 40 Water 250 NaOH 4 Water 4 Clay filler 200 Water 200 Polyvinyl acetate emulsion-65% solids 50 Water 25 The 60 parts of the casein powder and the 40 parts of the soya bean flour were mixed into 250 parts of water to form a glue-base mix. To this glue-base mix there was added and mixed in 4 parts of sodium hydroxide dissolved in 4 parts of water, 200 parts of clay filler and 200 parts of water, 50 parts of a polyvinyl acetate emulsion comprising 55% solids, and 25 parts of water to form.- a glue-mix according to the teachings of this invention.

Example N0. VII

This example comprises the following:

The above constituents were processed into a glue-mix and the same tested by making a paper-wood-paper laminate from a Douglas fir veneer and 42 pound kraft liner board. The glue spread was 40 pounds per thousand square feet of double glue line, the temperature of pressing was about 200 F., the pressure was approximately 20 p.s.i., and press times were 1, 2, 4, 8, and 12 seconds.

The paper was pulled from the veneer immediately after 7 pressing. The results of the test, expressed in Percent paper fiber retained on wood, are as follows:

Press Time (Seconds) 1 2 4 8 12 Percent Paper Fiber Retained on Wood 1 10 50 particularly, diiferent alkalies may be used instead of sodium hydroxide and lime without departing from the scope and spirit of the invention, various fillers may be employed in place of those enumerated, and defoamers not mentioned may be used for the same purpose as the indicated defoamer. Obviously, many modifications and variations in the invention as herebefore set forth may be made without departing from the spirit or scope thereof and, therefore, only such limitations should be imposed as are expressly recited in the following claims.

We claim:

1. An adhesive consisting essentially of an intimate mixture of parts by weight of a proteinaceous material selected from the group consisting of soya bean, cotton seed, and linseed flours substantially free of oil, casein, dried blood, and mixtures thereof, approximately 11.9-189.7 parts by weight on the dry basis of an aqueous emulsion of polyvinyl acetate, water, and 4-60 parts by weight of an alkali component selected from the group consisting of sodium hydroxide, sodium silicate, lime, and mixtures thereof, the alkali being present in an amount sufiicient to cause the proteinaceous material to become soluble and dissolve in the water in the said mixture.

2. The adhesive of claim 1, the said proteinaceous material being soya bean flour.

3. The adhesive of claim 1, the said proteinaceous material being casein.

4. The adhesive of claim 1, the said proteinaceous material being dried blood. I

5. The adhesive of claim 1, the said alkali being sodium hydroxide.

6. The adhesive composition of claim 1 including clay as tiller.

7. An adhesive consisting essentially of an intimate mixture of 100 parts by weight of soya bean flour substantially free of oil, about 11.9189.7 parts by weight on the dry basis of an aqueous emulsion of polyvinyl acetate, Water, and about 5-28.7 parts by weight of an alkali component selected from the group consisting of sodium hydroxide, sodium silicate, lime, and mixtures thereof, the alkali being in proportion within the range stated to cause the soya bean flour to become soluble and dissolve in the water in the said mixture.

References Cited in the file of this patent UNITED STATES PATENTS 1,999,253 Norris Apr. 30, 1935 2,000,383 Fife May '7, 1935 2,444,396 Collins et al June 29, 1948 2,544,146 Erikson Mar. 6, 1951 2,788,305 Sheeran Apr. 9, 1957 

1. AN ADHESIVE CONSISTING ESSENTIALLY OF AN INTIMATE MIXTURE OF 100 PARTS BY WEIGHT OF A PROTEINACEOUS MATERIAL SELECTED FROM THE GROUP CONSISTING OF SOYA BEAN, COTTON SEED, AND LINSEED FLOURS SUBSTANTIALLY FREE OF OIL, CASEIN, DRIED BLOOD, AND MIXTURES THEREOF, APPROXIMATELY 11.9-189.7 PARTS BY WEIGHT ON THE DRY BASIS OF AN AQUEOUS EMULSION OF POLYVINYL ACETATE, WATER, AND 4-60 PARTS BY WEIGHT OF AN ALKALI COMPONENT SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE, SODIUM SILICATE, LIME, AND MIXTURES THEREOF, THE ALKALI BEING PRESENT IN AN AMOUNT SUFFICIENT TO CAUSE THE PROTEINACEOUS MATERIAL TO BECOME SOLUBLE AND DISSOLVE IN THE WATER IN THE SAID MIXTURE. 